Direct Sequence Spread Spectrum Signal Detection And Parameter Estimation

Direct sequence spread spectrum signals have been widely used for securecommunication and mobile communication known as Code Division Multiple AccessSystem. Because DSSS signals have many advantages such as anti-jammingcapability, low probability of interception, multiple access capability andso on.For the issue of reconnaissance of DSSS/BPSK signals damaged by strongadditive white Gaussian noise(AWGN), the followings are the main researchcontent in this dissertation: The signal detection theory of auto-correlationmethod(ACM) is researched. Based on analysis on the generation mechanisms ofauto-correlation peaks, ACM is combined with average technique in correlationdomain. Average technique not only smoothes noise correlation lines, but alsomakes all potential positions of generating auto-correlation peaks of DSSS/BPSK signals. The improved ACM obtains lower SNR limitation successfully.Furthermore, the application of higher-order statistics to DSSS/BPSK signalparameters estimation is studied. An approach based on fourth-order cumulate2-D slice is researched, which can estimate the carrier frequency and thesymbol period. Based on the estimation of the symbol period, dispreadingwithout the code is studied in this paper, in which the local code is gainedfrom the received DSSS/BPSK signals. So we can intercept DSSS/BPSK signalswith low SNR even if the spreading code is unknown.